It is, of course, common sense that 1989 was the defining moment of the last quarter of the 20th century. Who could possibly disagree? It closed a chapter of history that had been ushered in by the October revolution in 1917. It brought to an end the systemic challenge that communism had posed to capitalism, the belief that there was, indeed, an alternative. It allowed the United States to emerge as the undisputed superpower of a new century. It gave globalisation access to the former Soviet bloc from which it had been excluded: henceforth, globalisation could live up to its name.

That is an imposing list by any standards: an epochal event of enormous implication. But the most important event of the late 20th century? Let me present another candidate: 1978. What, you might ask. Why 1978? It was the year that Deng Xiaoping introduced his open-door reforms in China , which inaugurated a quarter-century of annual double-digit growth rates, resulting in the economic transformation of China. Compared with 1989, 1978 was admittedly a rather dull affair, however far-reaching its implications might have been. But 1989, on the other hand -notwithstanding the fact that it was bloodless and atypically good-natured - had more than a touch of the grand European political theatre. It was recognisably in the European revolutionary tradition. No contest there then.

Nor did 1978 have the elevated political meaning that attaches to 1989. The latter did not just exude political theatre: it had substance too. It closed an era of not just communist but also socialist history. From that moment on, the world acquiesced in capitalism: like it or lump it, there was no other alternative in town. The country that had carried the hopes of a systemic alternative had collapsed amid its own contradictions.

That is history on the grandest scale - 1978 cannot possibly compare. A communist country chose to turn its back on an era of egalitarianism and embrace the market. It took the first tentative steps towards capitalism. In that sense, interestingly, 1978 mirrored 1989, or even anticipated it. Unlike the Soviet Communist party, the Chinese Communist party chose to introduce capitalism. So in political terms, in the language of grand alternatives Europeans are so partial to, 1978 cannot hold a candle to 1989.

No, the case for 1978 must be established on quite different grounds. It involved the making of a very different kind of history. Ever since Britain's industrial revolution began in the late 18th century the world has been dominated by the west, namely Europe and the US . Until well after the middle of the last century, it was widely believed that those countries that had been on the receiving end of European colonialism were destined for a perpetual status of dependency and underdevelopment. The rise of east Asia showed that not to be the case. More dramatically, the transformation of China has decisively moved the global centre of gravity eastwards. The 21st century will be quite unlike the preceding two centuries, in which power was located in Europe and the US and the rest of the world consisted of mere supplicants and bit players.

Although 1978 is still recent, we are already a long way down the road to the creation of this very different world. So far the process has been overwhelmingly economic. Europe, for example, is therefore still largely oblivious to the fact and consequences of this transformation, not least what it will mean politically and culturally for our continent. As a sign of our parochialism - and almost historically coincident with the rapid rise of China - we have become increasingly obsessed with the "Islamic problem". So long a cipher of the US, and now mired in its own travails and sense of decline, Europe has grown myopic and introspective, a poor vantage point from which to see the future.

In fact, we can already begin to see the broader implications of China's transformation: its global search for oil and other commodities; its increasingly proactive diplomatic presence around the world, from south-east Asia and the Middle East to Africa and Latin America; and a rapidly growing nervousness in Washington about China's emergent global role. And we are still only at the very beginning of this process. I have been struck on this visit to Beijing by the rapidly rising sense of self-confidence that characterises attitudes here - the feeling that history is "on our side".

History is proving surprisingly fleet of foot. In the aftermath of 9/11 and in the build-up to the invasion of Iraq, few questioned the idea that the United States was likely to be the extant superpower for several decades to come. Few anticipated how quickly the neoconservative project would run into the sands - or that China would rise so quickly. The New American Century has ended before the new century has got into its stride. The story of this century - or the first half of it - will be the decline of the existing superpower and the rise of a new one: China.

The ramifications are enormous. Power will no longer be located primarily in the west. The assumptions that inform global discourse will cease to be overwhelmingly western. History will no longer be written with a hugely western bias. Chinese interests, history, values, attitudes and prejudices will become familiar to us all. Perhaps all of this does not lie so far in the future as we might think. In his speech at Yale University on his recent visit to the US, Hu Jintao, the Chinese president, talked of Chinese values and what they have to offer the world. Here in Beijing one can detect a growing confidence in a more assertive argument about the achievements and merits of the Chinese Communist party.

So what, then, of the argument concerning 1989 and 1978? Perhaps we should, indeed, see 1989 as the epochal book end of the 20th century, the event that brought it all to a close. And - with a little historical licence - we should regard 1978 more properly as marking the beginning of the 21st century, the event that ushered in a new epoch, though barely anyone could possibly have realised it at the time. It is worth remembering, too, that 1989 was first and foremost a European event, probably the last great global event that was also European that we will witness for a very long time to come. Of course, 1978 was a purely Chinese moment, albeit with huge global ramifications. What could be a more eloquent summary of their respective places in history?